Far‐field effects of Late Miocene subduction in the Eastern Carpathians: E‐W compression and inversion of structures in the Alpine‐Carpathian‐Pannonian region

Abstract

Kinematic and paleostress data constrain a Late Miocene E‐W compressional event that affected the entire Alpine‐Carpathian‐Pannonian system after 9 Ma and prior to 5.3 Ma. The maximum horizontal compression directions obtained from 110 stations show a mean σ1 orientation of 083°. Deformation is mainly strike‐slip. E‐W directed compression followed Early to Middle Miocene upper plate extension in the Pannonian Basin which was caused by the retreating subduction boundary in the outer Carpathians. This compressional event terminated Early to Middle Miocene eastward lateral extrusion of the Eastern Alps and reverted strike‐slip faults which bounded earlier extruded wedges such as the Salzachtal‐Ennstal fault, the Periadriatic fault, the Mur‐Mürz‐Vienna Basin fault system, and strike‐slip faults in the Western Carpathians. E‐W compression caused the reorientation of the extension direction of the Alpine crustal stack. East‐directed tectonic unroofing of the metamorphic domes in the central Eastern Alps terminated between 9 and 6 Ma and Early to Middle Miocene orogen‐parallel E‐W extension switched to Late Miocene N‐S extension which parallels modern topographic slopes. In the Pannonian Basin the change from synrift extension to Late Miocene compression during the postrift phase caused the pronounced postrift subsidence by stress induced downward flexure of the loaded lithosphere.We relate Late Miocene E‐W compression to coeval late‐stage west‐ directed subduction of the European plate below the Eastern Carpathians. Slab pull of the subducted plate caused subduction roll back and upper plate extension of the Pannonian area up to the Middle Miocene. Subduction slowed down and ceased when up to 60‐km‐thick buoyant continental crust entered the subduction zone. During the short period of continued convergence E‐W ‐directed compressive stress was transmitted across the subduction boundary into the upper plate. Compressive stress was transferred through the uppermost brittle crust of the earlier extended Pannonian region into the Eastern Alps, up to 1400 km behind the subduction zone. E‐W compression terminated during the Pliocene when the Pliocene to recent NNW‐SSE compressive stress field was established in Central Europe.